This invention relates in general to apparatus for sorting animals below a predetermined size, and more particularly to a size sorting and control gate which is efficiently and simply operable in a variety of modes.
Various types of gates are known in the prior art for sorting animals below a predetermined size, and which are especially suited for swine. It is known to the prior art, that in many animals, including swine, the width of the animals generally correlates to their weight and to their age. Older animals are generally not marketable as quality stock or as prime meat to the various slaughtering houses. Various gates have been used in prior art in conjunction with buildings, fences or other enclosures to separate the animals below a predetermined size or weight from the balance of the livestock.
One of the main problems with prior art size sorting gates is that the size of the animal is not tested before the animal begins passing through the gate. In some prior art devices a pivoting element allows passage of the animal through the gate and also limits the size of animals therethrough. Animals of a size which are too large to pass through the gate often become pinched by the gate. The pinching phenomenon is caused by the fact that the pivoting element is usually resiliently or gravitationally biased toward the closed position. When the animal realizes that he will not be able to pass through the gate and begins backward movement, the pivoting element tends to remain biased against the animal and moves back toward the closed position as the animal begins to move backward. In some instances, the animal will not be released from the pivoting element of the gate until the operator of the gate is able to release him. Depending on the type of gate, periodic supervision may be required to prevent the loss of stock and to enable the sorting process to resume.
Many of the prior art gates have a structure which permits the sorting process to operate in only one direction. Often the gate is used in installations where size sorting in either direction is desirable. Time-consuming disassembly and reassembly of the apparatus may be required with prior art devices to achieve the reversible operation.
Some prior art devices are further characterized by inefficient use of the area of the gate. Due to the width adjustment means used in the gate, much of the area of the gate may be unusable. The unusable area further adds to the cost, bulkiness and inefficiency of the gate.